The molecular and functional characterization of E2F-5 transcription factor.
The E2F activity plays a critical role in the control of cell cycle and action of tumor suppressor proteins and is also a target of the transforming proteins of small DNA tumor viruses. We describe here molecular cloning and functional characterization of a fifth member of the E2F family of transcription factors. E2F-5 protein is more homologous to E2F-4 (72% amino acid identity) than to E2F-1, E2F-2, and E2F-3 (35% amino acid identity). Based on structural and functional criteria, the E2F family appears to comprise two distinct sub-families, one composed of E2F-1, E2F-2, and E2F-3 and the other composed of E2F-4 and E2F-5, E2F-5 mRNA is expressed in a wide variety of human tissues. The protein is expressed as multiple species ranging in size from 46 to 54 kDa as a result of differential phosphorylation. The expression of a reporter gene containing E2F binding sites in the promoter is transcriptionally activated by E2F-5 in a cooperative manner with the DP-1 protein. The interaction between E2F-5 and DP-1 is demonstrated using a two-hybrid system in mammalian cells. We have also demonstrated the presence of a strong transactivation domain at the carboxy terminus (273-346 amino acid residues) of E2F-5 protein.
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Virology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India. yash@iegebnd.ernet.in
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D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D050704:E2F4 Transcription Factor; D050700:E2F5 Transcription Factor; D017930:Genes, Reporter / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000032:analysis; D016415:Sequence Alignment; D017421:Sequence Analysis; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics; D014162:Transfection / Q000235:genetics
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050704:E2F4 Transcription Factor; D050700:E2F5 Transcription Factor; C092558:E2F5 protein, human; D012333:RNA, Messenger; C493735:TFDP1 protein, human; D050680:Transcription Factor DP1; D014157:Transcription Factors